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Here is a simple and fun experiment with water that you can show your friends. A little magic and they will be impressed with your skillsand knowledge! Did you ever put ice cubes into a full glass of water and have the water spill out? There wasn’t enough room for all of thewater and the ice. We’ll play with that idea and see what happens.

All you’ll need is a glass, some water and a box of paper clips. Your mom or dad might have some clips in their desk drawer.

1. Take the glass and fill it with cold water. Fill it until the water level reaches the rim of the glass.
2. You can then show the glass to your friends, your mom and dad, or your sister and ask them to predict how many paper clips you can drop into the glass until the water spillsout. Write down their guesses.
3. Then, you can start dropping the paper clips in the glass. But as you do, have your friends count out loud the number of clips as you drop them in. Do it carefully though, and only one clip at a time. Keep going until the water starts to overflow.
4. Surprise! The glass will hold almost the whole box ofpaper clips! Check the predictions you wrote down and see if any of your friends came close. You can ask the person who got closest to theright number how they figured it out.
5. If you have an eyedropper, you can do the same experiment without the paper clips. Take predictions from your friends then start slowly squeezing the eyedropper so drops come out and start counting to see how many get into the glass before it starts to overflow.

Here’s what happened:

When you dropped the paper clips in the glass, the water level increased by the amount equal to the volume, or size, of the paper clip that was put in the water. If you’ll look carefully at the side viewof the glass, you’ll see that the water level is rising higher than the rim of the glass. There is a special force that comes into action that allows the water to pile up like a small mound above the rim of the glass.

Water is made up of many, very small units of molecules. Each of these molecules is just like a tiny magnet with a negative end and a positiveend. The positive end of one molecule attracts the negative end of another molecule. All of the molecules are attracted to each other because of this. This attracting force is called “cohesion”. Raindrops are shaped like little round balls because of this samereason. The cohesion forms a bond at the surface of the water called surface tension. This is what allows the water to create its small mound at the top of the glass. But gravity takes over this force as the mound gets higher causing the water to spill over the sides of the glass.